Separate Accipitriformes from Falconiformes

Effect on SACC: This would split our current order Falconiformes into two,
with only the Falconidae remaining in the Falconiformes.

Background: Most classifications, including ours, recognize a broadly
defined Falconiformes to include not only the Falconidae but also all the
hawks, eagles, kites, and relatives plus Pandionidae and Sagittariidae.Without doing a thorough literature
review, I think I can get away with saying that there has always been some
doubt about the monophyly of broad Falconiformes.Google gives something like 49,00 hits
on Accipitriformes, including an official Wikipedia entry, and Google Scholar produces
492 citations that use Accipitriformes.Other than the obvious superficial similarities, I am not aware of any
solid genetic data that supports the monophyly of our current Falconiformes.Livezey & Zusi (2007) consider the
Strigiformes as sister to broadly defined Falconiformes, with Pandion sister to Falco +Polyborus.However, this same morphological
analysis still supports a sister relationship between Gaviiformes and
Podicipediformes, which is not consistent with any genetic dataset.Therefore, many conclude that even
sophisticated morphological analyses cannot distinguish convergence from true
relationships.

New data:Hackett et al.’s (2008)massive
analysis set new standards in gene sampling: 32 kilobases of aligned DNA
sequences that included 19 nuclear loci.They found strong support (98% Maximum Likelihood bootstrap) for a node
(“F”) that includes Falconiformes broadly defined plus Strigiformes …. But that
clade also includes Passeriformes, Psittaciformes, Cariamiformes, Piciformes,
Coraciiformes, Trogoniformes, and Coliiformes … and thus only marks one of the
major groups of modern birds.The nodes
within this clade are not as strongly supported, but Node B, with 73% bootstrap
support shows Falconidae as sister to Psittaciformes + Passeriformes.[Tangentially, I am impressed with the
similarities between falcons and parrots that include the bony tubercle in the nares, the notched mandible, and nesting biology – yes, I
recognize that tallies of similarities do not count per se].The branching pattern among the
remaining groups is probably best considered a polytomy, except for Node D,
which shows Leptosomus of Madagascar
as sister to Coraciiformes + Piciformes + Trogoniformes.Sagittariidae + (Pandionidae +
Accipitridae) is supported as a monophyletic group with 100% support.

Analysis and
Recommendation:Given the absence of any
non-morphological data that I know of that supports the monophyly of broadly
defined Falconiformes, given that the best and most thorough analysis to date
does not support this monophyly, and given the long history of doubts
concerning this monophyly reflected in widespread use of Accipitriformes, I
conclude that he burden-of-proof now lies on those who would consider our
Falconiformes as monophyletic …and
so I recommend a YES on this.However, as pointed out to me by Mike Braun, statistically one cannot
reject the possibility that the traditional Falconiformes is monophyletic – to
quote from an active MS by Dave Steadman et al. “while none of the analyses
in Hackett et al. (2008) supported monophyly of the traditional Falconiformes,
these same analyses were not able to reject monophyly of this group.”So, a NO vote
would indicate that the possibility of monophyly has to be rejected, and a YES
vote would indicate that support for them as a monophyletic group is
uncorroborated and that nonmonophyly is strongly suggested by the data.

Comments from Stiles: “YES. The massive data from the Hackett et al. study in
particular make it clear that the traditional Falconiformes is polyphyletic,
with the adaptations for diurnal raptorial habits being convergences between
the falcons et al. and the acciptrids et al.; hence separate orders are clearly
justified.”

Additional comments
from Remsen:“With respect to Manuel’s point
concerning Cathartiformes, the Hackett et al. data do not confirm a
monophyletic Accipitriformes if Cathartidae is included.Close, yes, but not necessarily forming
a monophyletic group.Further, I
support Order rank for cathartids regardless of possible sister status with
accipitrids because this lineage is as old or older than most lineages ranked
as orders.”

Comments from
Jaramillo: “YES – This
is indeed an amazing example of convergence, and I accept that it makes sense
to separate Accipitriformes from Falconiformes. I have also been impressed with
similarities between parrots and falcons, once I thought about them upon
reading this paper. There is a lot there to “chew on” that makes sense.”

Comments from Zimmer: “YES.I also
agree with Van regarding Order rank for cathartids.”